feat(tui): hover tooltip on status bar model segment

[marsmensch]

Summary

Hovering over the model+context segment in the Ink TUI status bar shows a FloatBox tooltip with the full model ID, provider, reasoning effort (when non-default), and fast-mode state.

Changes

• tui_gateway/server.py: add provider to _session_info() payload
• ui-tui/src/types.ts: SessionInfo.provider?: string
• ui-tui/src/app/interfaces.ts: add statusTooltip: null | { lines: string[] } to OverlayState (excluded from $isBlocked — informational only)
• ui-tui/src/app/overlayStore.ts: initialise statusTooltip: null; cleared by resetFlowOverlays()
• ui-tui/src/components/appChrome.tsx: buildModelTooltip() helper; provider prop on StatusRule; onMouseEnter/onMouseLeave on the pinned model+ctx Box fires patchOverlayState
• ui-tui/src/components/appLayout.tsx: pass provider={ui.info?.provider} to StatusRule
• ui-tui/src/components/appOverlays.tsx: render FloatBox when overlay.statusTooltip is set

Validation

	Before	After
Model segment hover	no feedback	FloatBox: model: … / provider: … / reasoning: … / fast mode: on
statusTooltip blocks input	—	no ($isBlocked unchanged)
tsc --noEmit in changed files	clean	clean
npm run build (ui-tui)	✓	✓

[marsmensch]

This PR is provided mainly as usability enhancement similar to Hermes Desktop this PR

[teknium1]

Thanks for the focused TUI usability contribution. The feature premise remains valid on current main: the model/context segment at ui-tui/src/components/appChrome.tsx:575-592 has no hover handling or tooltip rendering.

Problems

• Current main already emits provider from _session_info() at tui_gateway/server.py:3373 (and the lazy path preserves it at :5466-5467), so the backend hunk is redundant.
• The proposed tooltip is rendered through FloatingOverlays, which is composer-relative (ui-tui/src/components/appLayout.tsx:355-367; appOverlays.tsx:162). The default status bar is top-mounted (uiStore.ts:29, appLayout.tsx:353), so this does not place the tooltip next to the hovered status segment.
• No tests cover the new hover/state/wire behavior; current focused suites exist under ui-tui/src/__tests__/appChromeStatusRule.test.tsx and tests/tui_gateway/test_reasoning_session_scope.py.

Suggested changes

• Salvage only the TypeScript/UI plumbing; omit the already-landed backend field.
• Mount the tooltip in status-bar-relative layout and cover top/bottom status-bar placement plus the non-blocking overlay invariant.

Automated hermes-sweeper review.

[teknium1]

Current main already emits this field from _session_info() at tui_gateway/server.py:3373, and _lazy_resume_info() preserves a provider too at :5466-5467. Please omit this redundant backend hunk when salvaging the UI change.